The International epidemiologic Databases to Evaluate AIDS (IeDEA) network assembles observational data from seven large regional research cohorts-representing over 500 HIV clinics around the world-to address research questions about the HIV/AIDS epidemic. The substantial time and effort required to harmonize data for multi-cohort collaborations with so many sites can lead to research delays, particularly given heterogeneity in data management capacity, database design, and data management. The goal of the Harmonist project is to develop the Harmonist toolkit, a software and standards package that will enable HIV observational research networks to coordinate large-scale research projects and apply data management best practices more effectively and efficiently. The toolkit will be built as a series of flexible plugins to the widely used Research Electronic Data Capture (REDCap) system, which is in use at over 1,600 institutions in 92 countries (as of mid-2015.) Harmonist features will include web-based tools for secure data exchange, data quality checking, and scientific project and portfolio management. The Harmonist project aims to (1) design and implement the Harmonist toolkit; (2) establish a consortium of Harmonist users within the IeDEA network, while providing mentorship to IeDEA and others on the use of the software, related data standards, and best data management best practices; and (3) measure the impact of the Harmonist toolkit on the data management and workflow processes of the IeDEA network. This proposal is a collaboration between research informatics experts at Vanderbilt University and all seven regional networks of the IeDEA consortium. This partnership ensures all components of Harmonist address real-world user needs in a practical manner and provides the toolkit with a dedicated user base. We believe that these research tools can reduce the time and effort needed for critical data management and administrative tasks that underlie the role of observational HIV cohorts studying the global epidemic. A modular infrastructure, as proposed, can adapt to diverse research settings and expand to include new data types and sources as the understanding of HIV evolves. The resulting shareable software and mentoring resources will provide tangible immediate and long-term benefits to IeDEA as well as the broader HIV research community.